ABSTRACT
Although Cha et al. were the first to achieve a live birth after IVM in a recipient of a donated oocyte2, it was Trounson et al. who first successfully transferred embryos in the same cycle in which the immature oocytes were retrieved using ultrasound guided transvaginal aspiration of small follicles3. One of the challenges of this method is to prepare the uterus in only a few days between the oocyte retrieval and embryo transfer. Because immature oocytes are usually
retrieved before the dominant follicle develops, the endometrium is exposed to relatively low levels of estradiol by the time of immature oocyte collection (IOC). As a result, there is a dyssynchrony between the phase of the endometrium and the cleaved embryo. This is thought to be one of the reasons for the low success of the early days of IVM development4. Since then the clinical outcome of IVM has greatly improved and protocols for endometrial preparation have been developed.
